MAN Diesel & Turbo has won an order from US-based energy firm Chevron to power each of its two new lightering vessels with a MAN B&W 6G70ME-C9.2 prime mover.
The vessels will be equipped with a MAN Diesel & Turbo EGR (exhaust gas recirculation) system to help their ME-C prime movers meet Tier III emission standards.
The engines will also retain the ability to switch to Tier II operation when outside of environmental control areas (ECA).
Both vessels are scheduled to be delivered in 2014; the engines for the first vessel are expected to be delivered in December 2012 while the second set of engines will be installed in early 2014.
Chevron has also ordered one MAN 8L27/38 and two MAN 7L21/31 gensets for each vessel, which Doosan Engine will build along with the G-type main engines in South Korea.
MAN’s EGR system ensures full fuel flexibility, ranging from heavy fuel oil (HFO), which contains sulphur and forms NOx and SOx during combustion, to distillates and natural gas.
The system also cuts NOx by directing part of the exhaust gas back into the engine’s scavenge air, which reduces the oxygen content of the air in the combustion chamber, thus lowering the combustion temperature, resulting in a reduction of NOx formation.
MAN’s tests on the EGR system at its Diesel Research Centre in Copenhagen have demonstrated that the EGR system can achieve the IMO’s Tier III NOx emission requirements on its own.
MAN expanded its G-type engine portfolio with the addition of the G70ME-C9, G60ME-C9 and G50ME-B9 models in 2011.